5a,6,7,8,9,9a-hexahydro-9a-hydroxypyrido(2,1-b)benzothiazolium halides

ABSTRACT

NOVEL PHARMACOLOGICALLY ACTIVE COMPOUNDS HAVE BEEN PREPARED OF THE FORMULAE   2-(R2-C6H4-),3-R3,3A-HO,4-(R1-OOC-)-3A,4,5,6,7,7A-HEXA-   HYDROBENZOTHIAZOLIUM X(-), 9-(R1-OOC-),9A-HO-5A,6,7,8,   9,9A-HEXAHYDROPYRIDO(2,1-B)BENZOTHIAZOLIUM X(-), AND   9A-HO-5A,6,7,8,9,9A-HEXAHYDROPYRIDO(2,1-B)BENZOTHIAZOLIUM   X(-)   WHEREIN R1 AND R3 ARE SELECTED FROM THE GROUP CONSISTING OF HYDROGEN AND (LOWER) ALKYL; R2 IS SELECTED FROM THE GROUP CONSISTING OF HYDROGEN, (LOWER)ALKYL, NITRO, HALOGEN, (LOWER)ALKOXY, HYDROXY AND   -N&lt;(-R4-R5-)   WHEREIN R4 AND R5 WHEN NOT CONCATENATED ARE INDEPENDENTLY SELECTED FROM THE GROUP CONSISTING OF HYDROGEN AND (LOWER)ALKYL AND WHEN CONCATENATED FORM A RADICAL SELECTED FROM THE GROUP CONSISTING OF PIPERAZINYL, PIPERIDINYL, PYRROLIDINYL AND MORPHOLINYL; X IS HALOGEN.

United States Patent 3,775,421 a,6,7,8,9,9a-HEXAHYDRO-9a-HYDROXYPYRIDO [2,1-b]BENZOTHIAZOLIUM HALIDES Peter H. L. Wei, Springfield, Pa., assignor to Americln Home Products Corporation, New York, NY.

No Drawing. Original application Mar. 17, 1971, Ser. No. 125,410, now Patent No. 3,694,449, dated Sept. 26, 1972. Divided and this application May 15, 1972, Ser.

Int. Cl. C07d 31/50 US. Cl. 260-2943 B 2 Claims ABSTRACT OF THE DISCLOSURE Novel pharmacologically active compounds have been prepared of the formulae T CZ NRa G H I and wherein R and R are selected from the group consisting of hydrogen and (lower)alkyl; R is selected from the group consisting of hydrogen, (lower) alkyl, nitro, halogen, (lower) alkoxy, hydroxy and wherein R and R when not concatenated are independently selected from the group consisting of hydrogen and (lower) alkyl and when concatenated form a radical selected from the group consisting of piperazinyl, piperidinyl, pyrrolidinyl and morpholinyl; X is halogen.

CROSS REFERENCE TO RELATED APPLICATIONS This application is a division of copending application Ser. No. 125,410, filed Mar. 17, 1971, now US. Fat. 3,694,449.

DESCRIPTION OF THE INVENTION This invention is concerned with the preparation of novel chemical compounds which are pharmacologically active as central nervous system depressants. They are useful as calming agents for mammals.

The compounds are of the formulae:

R X i 3 3 i a, (I) 1 (:1)

and

on x

3,775,421 Patented Nov. 27, 1973 wherein R and R are hydrogen and (lower)alkyl; R is selected from the group consisting of hydrogen, (lower)- alkyl, nitro, halogen, (lower)alkoxy, hydroxy and wherein R and R when not concatenated are independently selected from the group consisting of hydrogen and (lower) alkyl and when concatenated form a radical selected from the group consisting of piperazinyl, piperidinyl, pyrrolidinyl and morpholinyl; X is halogen.

The compounds of Formula I may be prepared according to the following reaction scheme:

S R2 TC? |N on R; X

wherein R R and X are the same as hereinabove defined and R is lower alkyl.

The compounds are prepared by heating the reaction in an alcohol solution at a temperature of to for a period of 3 to 8 hours. The solvent is removed and the residue is triturated with ether and dimethoxyethane and the crude solid material which is collected can be recrystallized from ethanol.

Compounds of Formula H may be prepared by the following procedure:

bromic acid at a temperature of from 50 to 80 for a period of 20 to 40 minutes. After the solvent is removed at reduced pressure, the residue may be triturated with a solvent, such as acetone and collected.

As used herein the term (lower)alkyl is used to include hydrocarbon radicals such as methyl, ethyl, npropyl, i-propyl and n-butyl. The term halogen is used to include chlorine, bromine and iodine.

In the evaluation of the biological activity of the compounds of this invention, the in vivo elfects were tested as follows: The compound was administered orally or intraperitoneally to three mice (14 to 24 grams) at each of the following doses: 400, 127, 40 and 12.7 milligrams per kilogram of host body weight (m.p.k.). The animals were watched for a minimum of two hours during which time signs of general stimulation (i.e., increased spontaneous motor activity, hyperactivity on tactile stimulation, twitching), general depression (i.e., decreased spontaneous motor activity, decreased respiration), autonomic activity (i.e., miosis, rnydriasis, diarrhea) were noted.

The compounds of this invention induce central nervous system depressant eifects at a dose of 127 to 400 m.p.k. Thus the compounds of the invention, have demonstrated utility as pharmacologically active compounds in experimental and comparative pharmacology and are of value in the treatment of mammals, e.g., mice, rats, etc., who are responsive to treatment with central nervous system depressant agents. Specifically the compounds may be administered for the purpose of inducing a calming effect in mammals.

When the compounds of the invention are employed as described above, they may be administered alone or in combination with pharmacologically acceptable carriers, the proportion of which is determined by the solubility and chemical nature of the compound, chosen route of administration and standard pharmacological practice. For example, they may be administered orally in the form of tablets or capsules containing such excipients as starch, milk sugar, calcium carbonate and the like. They may be administered orally in the form of soutions which may contain coloring and flavoring agents or they may be administered by parenteral injection, e.g., intramuscular injection. The injectable solution may contain other solutes such as sodium chloride or glucose in a sufiicient quantity to render the solution isotonic.

The dosage of the pharmacological agents of the invention may vary with the route of administration and the particular compound chosen.

The following examples are not to be construed as limitations of the invention:

EXAMPLE 1 4-carboxy-2- (p-dimethylaminophenyl) -3 a,4,5,6,7,7a-hexahydro 3a hydroxy-3-methylbenzothiazolium bromide ethyl ester p-Dimethylamino-N-methylthiobenzamide was prepared following the procedure of Gaomaise and Chambers [1. Med. Chem., 11, 1205-8 (1968)].

An alcoholic solution of 6-bromo-2-carbethoxyclohexanone (4.9 g., 0.02 m) and p-dimethylamino-N-methylthiobenzamide (3.6 g., 0.02 m) was heated to reflux for hours. After removal of ethanol the residue was treated with ether. The residue upon standing solidified. The crude material after treatment with dimethoxy ethane weighed 5.0 g. and melted at 1758 C. Recrystallization from ethanol gave pure ethyl ester of 4-carboxy-2-(p-dimethylaminophenyl)-3a,4,5,6,7,7a-hexahydro-3a-hydroxy- 3-methyl-benzothiazolium bromide, M.P. 181-3 C.

Analysis.Calcd. for C H BrN O S (percent): C, 51.46; H, 6.14; N, 6.32. Found (percent): C, 51.26; H, 6.09; N, 6.30.

IR (KBr): 3.4 (OH); 5.8 (ester CO); 6.25 (C=N). NMR (CD01 5 7.3 (m., 4); 4.3 (q., 2, OCH 1.3 (t., 3, CH3); NCH 3.2 (s., 3); 3.7 (m.).

EXAMPLE 2 9-carboxy-5a,6,7,8,9,9a-hexahydro-9a-hydroxypyrido [2,1-b]benzothiazolium bromide, ethyl ester An acetic acid (60 ml.) solution of 6-bromo-2-carbethoxycyclohexanone (12.45 g. or 0.05 m) and Z-mercaptopyridine (5.55 g. or 0.05 m) was heated on a steam bath for 3 /2 hours. Upon cooling the solid that separated was collected and washed with dimethoxyethane and ether. The crude material was recrystallized from ethanol. The pure ethyl ester of 9-carboxy-5a,6,7,8,9,9ahexahydro-9a-hydroxypyrido[2,1-b]benzothiazolium bromide weighed 14.9 g. (82% yield), M.P. 206-207.

Analysi .Calcd. for C H NO S-Br (percent): C, 46.67; H, 5.03; Br, 22.18; N, 3.89; S, 8.90. Found (percent): C, 46.48; H, 4.97; Br, 22.07; N, 4.03; S, 8.70.

IR spectrum (KBr) showed the presence of ester absorption at 5 .8,u and the absence of keto carbonyl at 6.0;].- NMR spectrum (DMSO-d,,), 6 1.1 (t., J=7 Hz.), 4.1 (q., J=7 Hz.). Other aliphatic protons as complex multiplets absorbed at 1.8 to 2.2 and 3.6, the hydroxy proton was found at 6 4.8 was exchanged in D 0.

EXAMPLE 3 5a,6,7,8,Q,9a-hexahydro-9a-hydroxypyrido- [2,1-b1benzothiazolium bromide A 48% HBr (30 ml.) solution of ethyl ester 9-carboxy 5a,6,7,8,9,9a hexahydro-9a-hydroxypyrido[2,1-b] benzothiazolium bromide (6.0 g.) was heated on a steam bath. Gas evolution ceased at the end of the reaction period (3 hours). The solvent was removed in vacuo and the residue treated with benzene and the benzene was also removed. The residue was finally treated with acetone and the solid collected which weighed 4.4 g. Upon recrystallization from ethanol pure 5a,6,7,8,9,9a-hexahydro 9a hydroxypyrido[2,1-b]benzothiazolium bromide melted at 21315 C.

Analysis.Calcd. for C H NOS-Br (percent): C, 45.83; H, 4.90; Br, 27.73; N, 4.86; S, 11.13. Found (percent): C, 45.66; H, 5.09; Br, 27.40; N, 4.98; S, 11.16.

IR spectrum (KBr) showed the disappearance of carbonyl absorption. NMR (DMSO-d,;): 6 8.5 (m.); 4.6 (t.); complex multiplet 1.8 6.

By analogous methods the chloride and iodide salts may be obtained.

EXAMPLE 4 9-carboxy-5a,6,7,8,9,9a-hexahydro-9a-hydroxypyrido [2,1-b]benzothiazolium bromide A 48% HBr solution (40 ml.) of 9-carboxy-5a,6,7,8, 9,9a-hexahydro-9a-hydroxpyrido[2,1 b]benzothiazolium bromide ethyl ester (5.0 g.) was heated gently in a hot water bath for 30 minutes. The solvent was removed at reduced pressure and the solid residue (3.0 g.) after treatment with acetone was collected, and dried in a drying pistol at reduced pressure to afford product, M.P. -5.

Analysis.-Calcd. for C H NO S-Br (percent): C, 43.38; H, 4.25; Br, 24.05; N, 4.22; S, 9.65. Found (percent): C, 43.08; H, 4.46; Br, 23.77; N, 4.26; S, 9.83.

IR (KBr) 3.5a (OH); 5.85 (carboxyl CO). NMR (DMSO-d 6 8.5 (m.); aliphatic, 1.9 (m.).

By methods analogous to those employed in Example 1, the following compounds are prepared:

TABLE I 4-carboxy-2-(p-nitrophenyl)-3a,4,5,6,7,7a-hexahydro-3ahydroxy-3-ethylbenzothiazo1ium bromide, methyl ester 4-carb'oxy-2- (p-toluene) -3a,4,5,6,7,7a-hexahydro-3 ahydroxy-3-methylbenzothiazolium chloride, n-propyl ester 4-carboxy-2-(p-bromophenyl)-3a,4,5,6,7,7a-hexahydro- 3a-hydroxy-3-methylbenzothiazolium bromide, ethyl ester 

